Fuel Injector Balance Test

Test Results: Combine all of the injector pressure drops and divide this number by the amount of injectors available. This is the average pressure drop. Each individual injectors pressure drop value must be within 10 kPa (1.5 psi) of the average pressure drop value.

Circuit Description
The scan tool first energizes the fuel pump and then the injectors for a precise amount of time allowing a measured amount of fuel into the manifold. This causes a drop in system fuel pressure that can be recorded and used to compare each injector.

Test Description

Caution: Wrap a shop towel around the fuel pressure connection in order to reduce the risk of fire and personal injury. The towel will absorb any fuel leakage that occurs during the connection of the fuel pressure gauge. Place the towel in an approved container when the connection of the fuel pressure gauge is complete.

3. The engine coolant temperature must be below the operating temperature in order to avoid irregular fuel pressure readings due to Hot Soak fuel boiling.
4. The fuel pressure should be within the specified range with the fuel pump running. If the fuel pressure is not within the specified range, go to Fuel System Diagnosis.
5. Allow the fuel pressure to stabilize about 3 minutes. On a hot vehicle fuel pressure may increase due to fuel expansion after the pump stops running. This is a normal condition but the fuel pressure should stabilize and hold. The fuel pressure should reach a steady value. If the fuel pressure does not reach a steady value, refer to Fuel System Diagnosis. Component Tests and General Diagnostics
6. If the pressure drop value for each fuel injector is within 10 kPa (1.5 psi) of the average pressure drop value, the fuel injectors are flowing properly. Calculate the pressure drop value for each fuel injector by subtracting the second pressure reading from the first pressure reading. Refer to the illustration.